Two Pieces of a Broken Heart
by shewhodreamsofthe-enterprise
Summary: Leonard Horatio McCoy always saw James Tiberius Kirk as an only child. He never mentioned talk of any siblings, or any cousins for that matter. That's how it always was, until Karson Treadway enlisted in Starfleet. That's how it always was until Jim introduced Karson as his younger sister. / McCoy/OC. Rated M because I'm paranoid.
1. Prologue

**A/N: Okaaaaay! So, this is my first Star Trek fanfiction that I've been actually proud enough of the idea to jot down on **_**paper. **_**I haven't had this beta'd, so please ignore any stray grammar/spelling problems and mistakes. ENJOY. :D**

_**Gene Roddenberry and J.J. Abrams own the characters of Star Trek. I do not. I am not gaining any monetary value for writing this work of fiction. I am simply writing this for my and other's enjoyment. Please, do not sue me. **_

* * *

"Can I at least talk to her, Jocelyn?"

"She's upstairs doing her homework, Leonard. She doesn't need any distractions right now."

"Oh, come on, she can take a five minute break. She's twelve, not a college student."

Jocelyn sighed heavily on the other side of the comm. "I'm sorry, Len. She doesn't like being distracted when she's doing algebra. You know how stubborn she gets."

Leonard McCoy grimaced and pursed his lips, his annoyance evident on his face. Jocelyn would never know how truly annoyed he was, because she was on the other side of the country, in Macon, where he belonged. No, he was stuck in San Francisco, California, at this God forsaken Starfleet Academy—approximately 2,559 miles away from his precious daughter, Joanna. Joanna, with her big blue eyes and curly brown locks and the mess of freckles splattered across her nose and cheeks, and those two crooked front teeth.

Leonard didn't understand why Jocelyn kept Joanna from him. The intensity that both Joanna and he himself pestered her to talk to the other was enough to make someone scream, but she never gave in. She came up with the same over used excuses every time. Just because she'd won her in the divorce, didn't mean she wasn't his daughter anymore, and that he didn't have the right to talk to her. He _did_ have 50% custody of the adorable twelve year old, whether the bitter woman that was her mother wanted to admit it or not.

"Right, fine. Good bye, Jocelyn." Without bothering to hear her response, Leonard closed the comm with a harsh snap and tossed it onto his cot. He let out a broken sob. The medical cadet dropped his head into his hands and simply cried.

(~~*~~)

In the three years that Jim and Bones had come to know each other, Len knew everything there was to know about Jim Kirk. He knew his birthday (then again, what Starfleet cadet didn't?), the age he lost his first tooth, his first kiss and who it was with, how old he was when he lost his virginity and who it was to (although he was a bit embarrassed of it), and why he had joined Starfleet. He knew his favorite color, he knew both of his parents' names. The color he wished the sky was, his dream girlfriend. He knew what the color of the pair his lucky underwear was, and he knew why he'd chosen his dorm room so close to the girls' showers.

However, in the three years that he had known James T. Kirk, Leonard had never known he had a sister.


	2. Chapter One: Awkward Introductions

**A/N: I am so pleased on how well this is already going! Thank you to everyone that has favorited and followed this fic. I am trying very hard to get this ball rolling, but I'm having troubles with getting things down on paper and typing it up. Bear with me! I will update as often as I can. I am dedicating this awkwardly written chapter to my newest fanfic-writing-therapist, asterphoenix247 . YOU'VE HELPED ME SO MUCH, YOU HAVE NO IDEA.**

**Please review and let me know what I could add or improve on! Favorite, follow, whatever. (: Enjoy. **

It was a bright and sunny Monday morning in San Francisco. The dry air smelled of ocean water and the heated pavement beneath Leonard McCoy's feet as he approached the medical pavilion. Newly recruited cadets scurried nervously around the campus of Starfleet Academy, mint condition PADDs tucked under their arms like school children.

From the corner of his eye, Len spotted a blonde barreling toward him through the sea of maroon uniforms and caps, with a figure trailing hurriedly behind him. He gave a short eye roll. "I'm not sneaking you a hypospray that cures hangovers anymore, Jim. My advisor caught me and threatened academic suspension."

"No, no," Jim Kirk panted. "I do not need any more hyposprays." He pulled the figure, who stumbled clumsily, out from behind him. "I want to introduce you to someone. This is my sister."

She was short—from his calculations, Len could tell she was about five feet, two inches. She had chocolate brown hair that fell to her shoulders, and eyes the same color to match. She had a smattering of freckles all across her face. She reminded Len of one of Joanna's antique _American Girl _dolls—she definitely looked like one. At the same time, though, he saw someone else in her… Someone he couldn't quite put his finger on.

"Bones, this is Karson. Karson, Bones."

Len gave the girl a tight smile. She was a _girl, _wasn't she? Not that he doubted that she was female, but whether or not she had even started puberty. She definitely wasn't as…_developed_ as most women Len had seen, but he'd never admit he was looking. Surely she wasn't much older than 19.

"It's nice to meet you, Doctor McCoy," Karson spoke confidently. She gave him a sparkling smile—yup, she we definitely related to Jim. She had that same arrogantly confident glint in her eye when she smiled. The same _screw the rules _attitude. Again, he'd never admit that he had noticed.

Clearing his throat, Leonard spoke, "H-How exactly do you know my name? It's not often that someone refers me by my professional title."

"I've read some of your published medical journals. I recognized you from the picture on the inside cover. Your writings in Macon have worked wonders at the research center that I have worked at."

Len was surprised. Not only because of the fact that she _knew who he was,_ but of what she just said. _"-the research center that I have worked at." _Normally, research centers in any field required a doctorate degree. She was older than Len thought she was, or maybe she entered medical school early. "Oh? I'm surprised that anyone outside of Georgia knew I even existed." He let out a relaxed chuckle and rocked back on his heels. "What do you do?"

"I'm a nutritional biochemist. But I recently went back to school to get my associate's degree in bioengineering."

Okay, either she was _much _older than he thought she was, or she started college at a _very _young age. He glanced at Jim. The bastard was grinning from ear to ear at Leonard's evident surprise.

"How old are you exactly?"

"17."

Well, didn't he feel like a pervert? He had just assessed a 17 year old girl's body on whether or not she was _developed. _Leonard's eyebrows shot up. A PhD took about 6 years, plus an associate's degree? That's eight years of her life, put off for school when she should have been experiencing childhood. "So, you started college when you were nine, then?"

She nodded, another proud smile sprouting across her pretty face. "Yes, sir."

_What are they putting in the water these days?_ Len wondered. "Well, that is very impressive, Miss…," _Fuck, what was her last name?_ "…Kirk."

Jim snorted. Karson looked mildly uncomfortable.

"No, no, sir, I'm not a Kirk. Jim's mother and step-father adopted me when I was a baby." Karson laughed. It was such a relaxed, happy sound. It reminded him of sweet tea on hot afternoons in Georgia. It was so nostalgic, Leonard's stomach heaved. "I go by my biological father's last name—Treadway."

The air left Leonard's lungs so fast he thought he might pass out.

"Treadway. Clay Treadway?"

Karson nodded, her curls bouncing. "Yep, he's married now, I think-"

"Yeah, sweetheart, he's married to my wi-" Len caught short. "Well, ex-wife, now," the doctor added with a grumble, his previous Southern charm long gone. Just the sound of his name made his insides churn, made him want to kick puppies, even. He had never in his life wanted to hurt someone so much until he met Clay back in high school.

Silence ensued shortly thereafter, and broke off with Jim's loud, unrelenting bark of a laugh.

"Glad you find this funny, Jim," Len mumbled under his breath.

"As long as it doesn't involve me, I find everything funny."

Karson cleared her throat quietly. "Unfortunately, my Pharmacology class starts here shortly. It was nice meeting you, Doctor McCoy." Without another word, Karson turned on the heel of her flat black boots and scurried off.

"Well, I think that went well," Jim murmured.

"Jim, since when did you have a sister?"

"Just because I never mentioned her doesn't mean she doesn't exist. Anyway, I think she likes you."

"You kidding? The look on her face when she walked off screamed 'I'm terrified of this creepy old doctor and his bitterness.'"

Jim simply rolled his eyes and clapped a hand on his shoulder. "She looks up to you, man. You've been her idol in medical research ever since she got her PhD. She practically worships you. She about pissed herself when I told her you and I were friends."

Len grimaced. That was an odd mental image that the doctor did not want to relive. Jim's filter between mind and mouth was obviously malfunctioning this morning. Then again, wasn't it always? "I never thought in a million years that Clay Treadway would have a daughter. _Especially _while he was in high school." He'd grown up with the bastard. They were in the same class. They were on the same science debate team, for Christ's sake. If he had a child at any point in time that was now 17, he himself had to have been 17 when the mother gave birth. He wracked his brain for any remembrance of any female in his alma mater that was pregnant by the time of his graduation. Nothing came up—

Except one.


End file.
